Model Rocket Motors These are the famous model rocket engines that made model rocketry the safe hobby it is today. They incorporate a safe, intelligent design, manufactured under precise and strict engineering tolerances. Estes model rocket engines have been proven consistent and reliable in more than 300,000,000 launches. They are the key to the outstanding safety record model rocketry has achieved over the past 38 years.
· The concept of a factory assembled model rocket engine is the foundation of this safe, scientific and educational activity! · 3% of all Estes engines are static-tested at the factory for reliability and adherence to performance specs. · All engines comply with the codes of the National Fire Protection Association and are certified by the National Association of Rocketry.
HOW DOES A MODEL ROCKET ENGINE WORK?
1. Insert engine into rocket. Insert igniter and igniter plug into engine. Place rocket over launch rod on launch pad, hook igniter clips to igniter U.S. Patent Nr. 5,509,354 This is the most likely cause if ignition failure. Ensure that the leads of the ignitor do not touch or cross each other.	2. When the launch button is pressed, the engin produces thrust and boosts the rocket into the sky.
	3. After the propellant is used up, delay is activated, allowing the rocket to coast.
	4. After delay, ejection charge is activated, deploying the recovery system.
WHAT SIZES ARE AVAILABLE?
Engines are available in a wide variety of sizes and power levels.  Type Total Impulse in Newton Seconds 1/4 A 0.0 - 0.625 1/2A 0.626 -1.25 A 1.26 - 2.50 B 2.51 - 5.00 C 5.01 - 10.00 D 10.01 - 20.00 E 20.01 - 40.00 F 40.01 - 80.00 G 80.01 - 160.00 H 160.01 - 320.00 and so on...
WHAT DO THE DIFFERENT COLOR ENGINES MEAN?
Each type of engine is printed in a different color: Single stage engines are printed green. Upper Stage engines are printed purple. (Upper stage engines can be used as single stage engines in lightweight rockets.) Booster engines are printed red. (Booster engines contain no delay or ejection charge.) Plugged engines are printed black. (They are used for R/C gliders and contain no delay or ejection charge.) Each engine has a letter-number-number code (e.g. B6-4)
TOTAL IMPULSE Unit = Newton-seconds (N-sec) This lener indicates the total power the engine produces. Total Impulse is measured in Newton-seconds. One Newton-second is the total impulse produced by one Newton of thrust for a duration of one second. A "B" engine (5 N-sec) can produce up to 5 newtons of thrust for 1 see, 10 newtons for 1/2 sec or any combination that equals up to 5 N-sec. (1 N = 0.225 Ibs.) AVERAGE THRUST Unit = Newton This number tells you the Average Thrust of the engine during thrust phase. The actual thrust varies during engine burn. The propellant may burn quickly giving a higher average thrust or burn slowly for a lower average thrust. Generally, higher average thrust is best for heavier rockets, lower average thrust is usually more efficient for smaller, lighter rockets. TIME DELAY Unit = seconds This number is the number of seconds between the end of the thrust phase and the activation of the ejection charge. The delay allows the rocket to coast to its peak altitude before the recovery system is deployed.
These are the thrust curves for most Estes Rocket motors.
These thrust curves cover most of the "Comercial" rocket motors from AeroTech.